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E. EEEDEIGK RICE, E HARTFORD, ooNnEorlcUfr, Assrenoa To HiMs'ELE UNITED STATES PATENT OFFICE.

AND JAMES A. REEDER, OF SAME PLAGE.

TAP-WRENCH.

SPECIFICATION forming part of Letters Patent No. 272,478, dated February 20, 1883.

Application tiled January 19, 1883. (Model.)

To all whom it may concern Be it known that 1, R. FREDRIOK RICE, of Hartford, in thecounty of Hartford and State of Connecticut, have invented certain new and useful Improvements in Tap-Wrenches g and I do hereby declare that the following is a full, clear, and exact'description thereof, whereby a person skilled inthe art can make and use the same, reference being had to the accompanying drawings, and to theletters of reference marked thereon.

Like letters in the figures indicate'the saine parts. v

' My invention relates to tap wrenches designed for grasping and turning screw taps when cutting a screw-thread.

The object of my invention is to providea tap-wrench which shall firmly grasp and hold the shank ot' the tap when in use, and be simpier and stronger than the ordinary scroll-tap wrenches which have been heretofore constructed. These latter have commonly received the pressure and strain from the jaws upon the scroll-ring which moved the jaws, whereas in myimproved construction the pressure is transmitted to the frame of the wrench.

In the accompanying drawings, illustrating myinventiou, Figurelis a view ofm y improved tap-wrench'with the top plate removed, so as to show the interior parts. Fig. 2 is a longitudinal section through the middle of the tapwrench with the cover on. Fig. 3 is a crosssection through the middle of the tool, with the parts inthe same position shown in Fig. 2.

A is a central solid box containing the working parts, and provided with handles B in the customary manner.

(l is a cover or plate, which is attached by. screws to the centralv box, A, as shown inthe drawings, so as to inclose the working parts in the box A. The bottom of the boxA and the cover C are provided with openings in the center A and C', through which the shank of the tap passes to the jaws.

D D are the jaws. These slide in and out from the center in grooves in the solid box A. In the center of the box A there is the solid boss E, forming part of the box and integral withit, which is cut through to form solid and Y'firm-cheeks for the sides of the jaws to bear against and hold them firmly at their working ends. The tops of the jaws also enter and slide in a groove in the cover. The inner ends of the jaws D are furnished with suitable nicks to hold the square on the shank of the tap.

F and F are curved wedges, which lie ina circular recess in the box A, between the cen-y tral boss, E, and the rim G. Their outer curved surfaces are ymade of the same curvature as the inner side of the rim G, and bear evenly against it. The inner curved surfaces of these wedges are made of a spiral form, .with a gradually-increasing radius, and bear against shoulders D ou the jaws D. When turned to the right from the position shown in Fig. 1 these wedges thus force the two jaws together to grip the tap, one

' side ofeach wedge acting against the rim G and the other directly upon the jaw. As the wedges are entirely separate and distinct parts, and are free to move outward, the pressure from the jaws is transferred through the thickness ot' the wedges to the rim G, which forms part of the solid frame of the wrench. In order toV move the jaws outward when the Wed ges are moved back or released, there are grooves H formed in the tops of the wedges, parallel to their inner surfaces,in which the pins J of the jaws slide. These pins act tordraw the jaws outward and hold the shoulders against the inner sides of the wedges, as will be readily understood from the drawings.

K is a screw-clamp, furnished with a milled head ou tside of the box A, and, passing through a slot in the rim G, is screwed into one of the v wedges, F. This serves'as a handle to operate the wedges and move the jaws out or in, which is done by sliding it back and. forth in the slot.

It also serves as a clamp to hold the wedges and jaws in a xed position, so thatthey cannot become loosened accidentally by turning.

in the screw, and thereby binding the wedge against the `rim G.

By means of my invention the pressure from the jaws'is exerted upon the solid part of the frame of the tap-wrench, and is not sustained' by a separate ring, which moves the jaws, as in tap-wrenches heretofore constructed.

What I claim as my invention isl. The combination of thejawsD D,the septhe box A, provided with the fixed rim G and aratevcurved wedges F F', and the box A, havguides for the jaws, and with the covering-plate ing the rim G, substantially as described. C, substantially as described.

2. The combination of the jews D, provided R. FREDRICK RICE. 5 with shoulders D and pins J, the wedges F, Witnesses: Y

provided with curved outer and inner surfaces EDWIN F. DIMOCK, and the grooves H, the clamping-handleK, and THEO. G. ELLIS. 

